Make field trials activated in the GPU process be reflected in browser.

content/browser/gpu/gpu_process_host.cc

Index: content/browser/gpu/gpu_process_host.cc
diff --git a/content/browser/gpu/gpu_process_host.cc b/content/browser/gpu/gpu_process_host.cc
index 8764010907cea33a8f5ed6bed108fd07ab166d0a..0cdbb542343a7ad5e135fa9097695f8e959dd81e 100644
--- a/content/browser/gpu/gpu_process_host.cc
+++ b/content/browser/gpu/gpu_process_host.cc
@@ -6,6 +6,8 @@
 
 #include <stddef.h>
 
+#include <algorithm>
+#include <list>
 #include <utility>
 
 #include "base/base64.h"
@@ -16,7 +18,8 @@
 #include "base/logging.h"
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
-#include "base/metrics/histogram.h"
+#include "base/metrics/field_trial.h"
+#include "base/metrics/histogram_macros.h"
 #include "base/sha1.h"
 #include "base/threading/thread.h"
 #include "base/trace_event/trace_event.h"
@@ -188,7 +191,7 @@ class GpuSandboxedProcessLauncherDelegate
 #if defined(OS_WIN)
   bool ShouldSandbox() override {
     bool sandbox = !cmd_line_->HasSwitch(switches::kDisableGpuSandbox);
-    if(! sandbox) {
+    if (!sandbox) {
       DVLOG(1) << "GPU sandbox is disabled";
     }
     return sandbox;
@@ -629,7 +632,7 @@ bool GpuProcessHost::OnMessageReceived(const IPC::Message& message) {
     IPC_MESSAGE_HANDLER(GpuHostMsg_AcceleratedSurfaceCreatedChildWindow,
                         OnAcceleratedSurfaceCreatedChildWindow)
 #endif
-
+    IPC_MESSAGE_HANDLER(GpuHostMsg_FieldTrialActivated, OnFieldTrialActivated);
     IPC_MESSAGE_UNHANDLED(RouteOnUIThread(message))
   IPC_END_MESSAGE_MAP()
 
@@ -908,6 +911,13 @@ void GpuProcessHost::OnGpuMemoryUmaStatsReceived(
   uma_memory_stats_ = stats;
 }
 
+void GpuProcessHost::OnFieldTrialActivated(const std::string& trial_name) {
+  // Activate the trial in the browser process to match its state in the
+  // GPU process. This is done by calling FindFullName which finalizes the group
+  // and activates the trial.
+  base::FieldTrialList::FindFullName(trial_name);
+}
+
 void GpuProcessHost::OnProcessLaunched() {
   UMA_HISTOGRAM_TIMES("GPU.GPUProcessLaunchTime",
                       base::TimeTicks::Now() - init_start_time_);